/**
   * Copyright (C) 2013 Ludwig Knüpfer <ludwig.knuepfer@fu-berlin.de>
   *               2015 Kaspar Schleiser <kaspar@schleiser.de>
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @ingroup     native_cpu
   * @ingroup     drivers_periph_timer
   * @{
   *
   * @file
   * @brief       Native CPU periph/timer.h implementation
   *
   * Uses POSIX realtime clock and POSIX itimer to mimic hardware.
   *
   * This is based on native's hwtimer implementation by Ludwig Knüpfer.
   * I removed the multiplexing, as xtimer does the same. (kaspar)
   *
   * @author      Ludwig Knüpfer <ludwig.knuepfer@fu-berlin.de>
   * @author      Kaspar Schleiser <kaspar@schleiser.de>
   *
   * @}
   */
  
  #ifdef __MACH__
  #include <mach/clock.h>
  #include <mach/mach_init.h>
  #include <mach/mach_port.h>
  #include <mach/mach_host.h>
  /* Both OS X and RIOT typedef thread_t. timer.c does not use either thread_t. */
  #define thread_t riot_thread_t
  #endif
  
  #include <time.h>
  #include <sys/time.h>
  #include <signal.h>
  #include <stdint.h>
  #include <stdlib.h>
  #include <string.h>
  #include <err.h>
  
  #include "cpu.h"
  #include "cpu_conf.h"
  #include "native_internal.h"
  #include "periph/timer.h"
  
  #define ENABLE_DEBUG (0)
  #include "debug.h"
  
  #define NATIVE_TIMER_SPEED 1000000
  
  static unsigned long time_null;
  
  static timer_cb_t _callback;
  static void *_cb_arg;
  
  static struct itimerval itv;
  
  /**
   * returns ticks for give timespec
   */
  static unsigned long ts2ticks(struct timespec *tp)
  {
      /* TODO: check for overflow */
      return((tp->tv_sec * NATIVE_TIMER_SPEED) + (tp->tv_nsec / 1000));
  }
  
  /**
   * native timer signal handler
   *
   * set new system timer, call timer interrupt handler
   */
  void native_isr_timer(void)
  {
      DEBUG("%s\n", __func__);
  
      _callback(_cb_arg, 0);
  }
  
  int timer_init(tim_t dev, unsigned long freq, timer_cb_t cb, void *arg)
  {
      (void)freq;
      DEBUG("%s\n", __func__);
      if (dev >= TIMER_NUMOF) {
          return -1;
      }
      if (freq != NATIVE_TIMER_SPEED) {
          return -1;
      }
  
      /* initialize time delta */
      time_null = 0;
      time_null = timer_read(0);
  
      _callback = cb;
      _cb_arg = arg;
      if (register_interrupt(SIGALRM, native_isr_timer) != 0) {
          DEBUG("darn!\n\n");
      }
  
      return 0;
  }
  
  static void do_timer_set(unsigned int offset)
  {
      DEBUG("%s\n", __func__);
  
      if (offset && offset < NATIVE_TIMER_MIN_RES) {
          offset = NATIVE_TIMER_MIN_RES;
      }
  
      memset(&itv, 0, sizeof(itv));
      itv.it_value.tv_sec = (offset / 1000000);
      itv.it_value.tv_usec = offset % 1000000;
  
      DEBUG("timer_set(): setting %u.%06u\n", (unsigned)itv.it_value.tv_sec, (unsigned)itv.it_value.tv_usec);
  
      _native_syscall_enter();
      if (real_setitimer(ITIMER_REAL, &itv, NULL) == -1) {
          err(EXIT_FAILURE, "timer_arm: setitimer");
      }
      _native_syscall_leave();
  }
  
  int timer_set(tim_t dev, int channel, unsigned int offset)
  {
      (void)dev;
      DEBUG("%s\n", __func__);
  
      if (channel != 0) {
          return -1;
      }
  
      if (!offset) {
          offset = NATIVE_TIMER_MIN_RES;
      }
  
      do_timer_set(offset);
  
      return 1;
  }
  
  int timer_set_absolute(tim_t dev, int channel, unsigned int value)
  {
      uint32_t now = timer_read(dev);
      return timer_set(dev, channel, value - now);
  }
  
  int timer_clear(tim_t dev, int channel)
  {
      (void)dev;
      (void)channel;
  
      do_timer_set(0);
  
      return 1;
  }
  
  void timer_start(tim_t dev)
  {
      (void)dev;
      DEBUG("%s\n", __func__);
  }
  
  void timer_stop(tim_t dev)
  {
      (void)dev;
      DEBUG("%s\n", __func__);
  }
  
  unsigned int timer_read(tim_t dev)
  {
      if (dev >= TIMER_NUMOF) {
          return 0;
      }
  
      struct timespec t;
  
      DEBUG("timer_read()\n");
  
      _native_syscall_enter();
  #ifdef __MACH__
      clock_serv_t cclock;
      mach_timespec_t mts;
      host_get_clock_service(mach_host_self(), SYSTEM_CLOCK, &cclock);
      clock_get_time(cclock, &mts);
      mach_port_deallocate(mach_task_self(), cclock);
      t.tv_sec = mts.tv_sec;
      t.tv_nsec = mts.tv_nsec;
  #else
  
      if (real_clock_gettime(CLOCK_MONOTONIC, &t) == -1) {
          err(EXIT_FAILURE, "timer_read: clock_gettime");
      }
  
  #endif
      _native_syscall_leave();
  
      return ts2ticks(&t) - time_null;
  }